Arrangement and method for controlling communication connections

ABSTRACT

Arrangements and methods for controlling communication connections in a packet-oriented communication system are provided. A communication master computer controls communication connections based on exchanged signaling messages of a respectively preset communication protocol and a service provider unit supplies communication services for establishing and controlling connections based on bi-directional communication service calls with a service user unit. An interface to couple the service provider unit with the service user unit is provided. Additionally an interface to couple the master computer with the service provider unit is provided. Parameters are extracted from a received signaling message for assignment to a communication service.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority to the German application No.10345548.5 DE, filed Sep. 30, 2003 and which is incorporated byreference herein in its entirety.

FIELD OF INVENTION

The invention relates to an arrangement and a method for controllingcommunication connections for packet-oriented real-time communicationbetween two communication users.

BACKGROUND OF INVENTION

As well as transmitting data, current packet-oriented networks are usedincreasingly for transmitting communication data or real-timecommunication data. The transmission of communication data via apacket-oriented network is often also referred to as Voice over IP orVoIP. The term VoIP thereby refers to a technology for transmittinguseful data, such as voice, and an exchange of signaling data forcontrolling connections via packet-oriented networks.

Two standard protocols for the implementation of VoIP, specificallyH.323 and SIP, are known for the packet-oriented transmission ofcommunication data between two users and for switching users andproviding performance features.

SIP (Session Initiation Protocol) is a standard proposed by the InternetEngineering Task Force (IETF) for signaling connections viapacket-oriented networks and is currently predominantly deployed in thefield of internet telephony and for further services such as conferenceinteractions, event notification, message transmission, etc.

The standard H.323 is an international ITU-T standard (InternationalTelecommunication Union—Telecommunication Standardization Sector) forvoice, data and video communication via packet-oriented networks,ensuring mutual interoperability of proprietary products.

For the implementation of packet-oriented communication technologies ina communication system, the problem frequently occurs that theabove-mentioned protocols H.323 und SIP have to coexist, in order to beable to link communication terminals operating according to therespective communication protocol. It is not however possible for a SIPcommunication terminal to communicate with an H.323-compatiblecommunication terminal without the provision of further technicaldevices.

Previous VoIP solutions have been based on so-called standalonesoftware. Standalone software refers to software installed in thecommunication terminal or—in more general form—in a client to processboth signaling data and payload data. One disadvantage of such asolution is that any change to the communication protocol and anyintroduction of new additional performance features can only beimplemented by updating said software at every terminal. For a companythis measure requires a great deal of configuration work and therefore asignificant cost expenditure.

A further problem is the complexity of said software. As new performanceand service features are introduced, said software becomes more and morecomplex and extensive. The software implemented in the communicationterminal—client software—not only has to identify newly addedperformance features, it must also be able to implement methods toexecute said performance features.

With extensive standalone software, integration into applications notprovided for communication purposes is problematic. To develop saidapplications, already existing VoIP functions generally have to beadapted or developed from new. Furthermore the integration of additionalperformance features from third party manufacturers is almost excluded.

Some VoIP applications provide programming interfaces for integrationinto other applications and these are known in specialist circles asApplication Program Interfaces, API. However a further compilationprocess is generally required to integrate said programming interfacesinto other applications.

The use of so-called gateways is known as a means to ensure theinteroperability of the VoIP communication protocols H.323 and SIP. Agateway thereby converts signaling data based on the SIP protocol to aformat suitable for H.323 and vice-versa. It is often the case herehowever that protocol elements of a respective communication protocolare incompatible with protocol elements of the other communicationprotocol. It is also often the case that one of the two communicationprotocols supports services, applications, processing methods, etc.which are not supported in the other communication protocol.

To avoid the problems associated with updating stand-alone software asdiscussed above, some service providers offer VoIP solutions asso-called web applications. Obtaining a so-called applet via apacket-oriented data network and integrating it in a browser environmentin the form of a so-called plug-in allows the execution of a VoIPfunctionality via a web browser. Such an above-mentioned executionimproves the above-mentioned update problem but offers no opportunityfor seamless integration into any applications.

SUMMARY OF INVENTION

The object of the invention is to provide a communication environment,the deployment of which avoids the problems of the prior art.

The object is achieved by the claims.

According to the invention at least one communication master computer isprovided in a packet-oriented communication system to controlcommunication connections based on exchanged signaling messages—forexample SIP or H.323—of a respectively preset communication protocol. Atleast one service provider unit is also provided to supply communicationservices for establishing and controlling connections based onbi-directional communication service calls with at least one serviceuser unit. These communication services are provided particularly as webservices. The service provider unit is configured with interfaces withthe at least one service user unit and with the at least onecommunication master computer and includes means for characterizing areceived signaling message and for extracting parameters contained inthe signaling message and for assigning to a communication service. Theservice provider unit also includes means for generating at least onesignaling message further to a communication service call of the atleast one service user unit.

One significant advantage of the inventive method is that thecommunication services for establishing and controlling connections aremoved from a communication terminal—such as a so-called SIP phone or acommunication terminal operating according to the standard H.323.—to acentral service provider unit.

The complex and time-consuming update measures that previously had to betaken in the service user units or clients are therefore not necessarywith the inventive means.

The inventive communication services advantageously take over all thesignaling tasks of the client, from the point of view of which theinventive service provider unit acts as proxy. The role of proxy meansthat all communication with the client takes place in both directionsbetween said client and the proxy.

The inventive arrangement proves to be particularly advantageous evenwith the provision of additional performance features that have to besupported in the communication system. This frequently occurring updatemeasure also only affects the service provider units, while only new ormodified abstract communication service calls occur for the service userunits.

One particular advantage of the preferably 3-tier architecture with alevel arranged between the communication master computers and theservice user units acting as communication terminals—implemented in theservice provider unit—is the loose coupling and simple integration ofcommunication services—in some instances in the form of so-called webservices—into other applications, whereby said integration isadvantageously both independent of the programming language used for theapplication and also independent of the operating system provided forexecution of the service user units or the application.

The communication services are advantageously independent of thecommunication protocols existing or co-existing in the communicationsystem and are therefore also suitable for deployment in communicationsystems with heterogeneous communication protocols.

Advantageous developments of the invention are specified in thedependent claims.

An exemplary embodiment with further advantages and configurations ofthe invention is described in more detail below with reference to thedrawing, in which:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1: shows a block diagram to illustrate schematically the logicallevels within an inventive communication system;

FIG. 2: shows a block diagram to illustrate schematically the signalingdata and useful data exchanged within the communication system and alsocommunication service calls;

FIG. 3: shows a chronological flow diagram to illustrate schematicallyan exchange of signaling messages and control messages to establish aconnection between a service user unit and a communication unit;

FIG. 4: shows a chronological flow diagram to illustrate schematicallyan exchange of signaling messages and control messages to establish aconnection between two service user units;

FIG. 5: shows a chronological flow diagram to illustrate schematicallyan exchange of signaling messages and control messages to establish aconnection between a communication unit and a service user unit;

DETAILED DESCRIPTION OF INVENTION

FIG. 1 shows a communication system 100 divided into three logicallevels LYR1, LYR2, LYR3. The communication system 100 is a part of apacket-oriented network (not shown). This means that each of thefunctional components described in more detail below has the capabilityof a packet-oriented data exchange with the packet-oriented network.

A first master computer 102(a) assigned to a first logical level LYR1has—in addition to further functional units (not shown)—a firstprocessing unit 106(a) and a first interface 104(a). A second mastercomputer 102(b) also assigned to the first logical level LYR1correspondingly has a second processing unit 106(b) and a secondinterface 104(b).

A proxy master computer unit assigned to a second logical level LYR2 andhereafter also referred to as the proxy server 120, is connected to thefirst interface 104(a) of the first master computer 102(a) and thesecond interface 104(b) of the second master computer 102(b) via thepacket-oriented network (not shown). In the drawing this “connection”via a packet-oriented network is shown with a solid line. Such a“connection” thereby serves only to illustrate a communication relationvia a—by its nature connectionless per se—packet-oriented network.

The proxy server 102 has—in addition to further functional components(not shown)—an integration unit 122, a processing unit 102(c) and aninterface 104(c).

The proxy server 120 is connected via its interface 104(c) to a firstand a second communication terminal 130(a), 130(b). The firstcommunication terminal 130(a) and the second communication terminal130(b) are assigned to a third logical level LYR3.

To illustrate interoperability with different communication protocols,it is assumed below that the first master computer 102(a) is a centraladministrative entity operating according to the H.323 communicationprotocol, also known in specialist terminology as a gatekeeper.

The second master computer 102(b) corresponds to an administrativeentity operating according to the SIP communication protocol. In thecase of the communication protocol SIP this administrative entity isgenerally subdivided into a plurality of units (not shown) such as a SIPproxy server, a redirect server, a registrar and a location server,while one unit in the form of the second master computer 102(b) is usedas the basis for the drawing for reasons of clarity.

The first master computer 102(a) exchanges messages configured accordingto the H.323 communication standard with H.323-compatible terminals (notshown) via an interface (not shown). In a similar manner the secondmaster computer 102(b) exchanges messages configured according to theSIP communication standard with SIP-compatible terminals (not shown) viaan interface (not shown).

At the first interface 104(a) of the first master computer 102(a)messages exchanged in the form of data packets are however notconfigured according to the H.323 communication standard. In a similarmanner the messages exchanged at the second interface 104(b) of thesecond master computer 102(b) are not configured according to the SIPcommunication standard. The messages exchanged at the first or secondinterface 104(a), 104(b) are specifically exchanged in a differentformat that can be processed for the integration unit 122 of the proxyserver 120, as will be examined in more detail below.

After this illustration of hardware components to describe the physicalstructure of the communication system 100, the functional units shown inFIG. 1 are considered below with regard to their function andcommunication relations in respect of each other. The three logicallevels LYR1, LYR2, LYR3 define an organization form according to aso-called 3-tier model, in which units in the form of hardware and/orsoftware exchange data with each other.

For the purposes of structural consideration, the units referred toabove as communication terminals within the third logical level LYR areintroduced as first and second service users 130(a), 130(b). A serviceuser 130(a) or 130(b) or a service user unit 130(a), 130(b) is oftenalso referred to in specialist circles as a client and it implementscalls for functions, which are provided for example by a so-calledservice provider or service provider unit—in specialist circles oftenalso referred to as a server.

The functions called by the service user units 130(a), 130(b) areprovided by the service provider unit 120 previously referred to as theproxy server. For the service user units 130(a), 130(b),

this service provider unit 120 therefore acts as a so-called serviceprovider.

The mode of operation of the logical levels LYR1, LYR2, LYR3 can now besummarized as follows based on this architecture of the communicationsystem 100:

-   The first logical level LYR1 provides native signaling functions of    communication protocols such as H.323 and SIP.-   The second logical level LYR2 abstracts these native signaling    functions and supplies these to the third logical level LYR3 in the    form of (VoIP) communication services as so-called web services.-   The third logical level LYR3 corresponds to client software. Based    on the supplied implementation of said client software a designer is    able to implement a VoIP solution using the communication services    provided by the second logical level LYR2. The client software    thereby includes only the functions which are essential for the    clients, i.e. the service users 130(a), 130(b) such as the    management of a useful data exchange and the codec functions used    for this. Service users 130(a), 130(b) use the conimunication    services provided by the second logical level LYR2 for execution in    their own applications. These applications are implemented for    example in a communication terminal or on a computer system.

The respective service user 130(a), 130(b) sends requests for theestablishment of a connection to the service provider 120 and awaitsconfirmation or rejection of said request. This request is independentof the communication protocol—SIP or H.323—used in the first logicallevel LYR1 for the actual establishment of the connection but isconfigured as a call for communication services. This call forcommunication services is protocol-neutral and is effected for examplebased on the XML standard (Extended Markup Language). If the request isconfirmed, the service user 130(a), 130(b) receives parameters with theconfirmation such as port number and coding method, which are to be usedfor the subsequent exchange of useful data (not shown). This exchange ofuseful data and associated media processing is completely separate fromthe exchange of signaling data.

Communication connections between different logical levels are describedin more detail below with further reference to the functional units inFIG. 1.

FIG. 2 shows an exchange of messages or function calls between differentfunctional units known to an extent from FIG. 1 and the logical levelsLYR1, LYR2, LYR3. For the sake of clarity the logical levels LYR1, LYR2,LYR3 are only symbolized by direction arrows unlike the diagram in FIG.1.

A further communication unit 242 is arranged in the third logical level242 in addition to the service users 230(a), 230(b).

Unlike FIG. 1 it is assumed in the exemplary embodiment to be describedbelow that two service provider units 220(a), 220(b) are arranged in thesecond logical level of the communication system 200 and only one mastercomputer 202 is arranged in the first logical level LYR1. The mastercomputer 202 is for example in the form of a central SIP administrationentity.

The communication unit 242 is correspondingly in the form of a SIPcommunication terminal and exchanges with the master computer 202 on thebasis of signaling messages SGN configured according to the SIPstandard.

The communication users in the method to be described below are inparticular the communication unit 242, the first service user 230(a) andthe second service user 230(b).

In the case of an existing communication connection between thecommunication unit 242 and the first service user 230(a), useful dataPLD1 is exchanged directly between the communication unit 242 and thefirst service provider 230(a).

A similar direct exchange of useful data PLD2 also takes place in thecase of an existing communication connection between the first and thesecond service user unit 230(a), 230(b).

The first service user unit 230(a) uses a first service call PR1 via thefirst interface 204(a) of the first master computer 220(a) to call upthe latter's communication services or web services.

The second service user unit 230(b) correspondingly uses a secondservice call PR2 to call up communication services of the second mastercomputer 220(b).

An exchange of data also takes place between communication services ofthe first master computer 220(a) and communication services of thesecond master computer 220(b) via a third service call PR3.

The functional units located in the first logical level LYR1 are onlyused in the method provided according to the invention, if a calling orcalled communication partner can only be addressed via one of thesupported communication protocols—SIP in the exemplary embodiment.

A request to establish a connection initiated from the third logicallevel LYR3, for example by the first connection taker 230(a) using thecommunication unit 242 is routed in such a case via the second logicallevel LYR2 to the first logical level LYR1, whereby necessary parameterswithin the signaling information—e.g. call number and characteristics ofthe calling user—are forwarded in corresponding messages orcommunication function calls PR1, PR2.

Signaling messages SGN are then exchanged between the calledcommunication unit 242 and the master computer 202 in the first logicallevel LYR1. The signaling messages SGN are used at the time ofestablishment of the communication connection for example to agree whichport and codec should be used for the communication to be set up. Afterthe end of this signaling phase, confirmation of a successfullyestablished connection and result parameters accompanying this arereturned via the second logical level LYR2 and via the third logicallevel LYR3 to the calling communication unit 242 for voice transmissionand monitoring of the communication connection.

From the point of view of the called communication unit 242 the exchangeof messages in the logical level LYR1 corresponds to communication witha SIP proxy server or in an alternative embodiment with an H.323gatekeeper, depending on which of the two communication protocols wasused to exchange signaling messages with the communication unit 242.

From the point of view of the calling first service user 230(a) in thethird logical level LYR3 this message exchange remains hidden. In thislevel LYR3 only abstracted communication services PR1 are called up andparameters returned relating to said services PR1.

If however the called communication partner is arranged in the thirdlogical level LYR3 like the calling communication partner, in otherwords for example in the case of a request for a connection between thefirst and second service users 230(a), 230(b), the connection isestablished directly on the second logical level LYR2.

For this purpose the service provider units 220(a), 220(b) arranged inthe second logical level LYR2 are responsible for all the steps requiredto establish the counection and the associated parameters, such as therequest for establishment of the connection, the capacity interrogation,request confirmation, etc.

FIG. 3 shows a chronological flow diagram with further reference to thefunctional units in FIG. 2 to illustrate schematically an exchange ofsignaling messages and control messages during the establishment of aconnection between the calling first service user unit 230(a) and thecalled communication unit 242.

The time lines 1,2,3,4 and 5 are assigned in this order to the firstservice provider unit 230(a), the second interface 204(a) of the firstservice provider unit 220(a), the first interface 204(c) of thecommunication master computer 202, the first processing unit 206(c) ofthe communication master computer 202, and the communication unit 242.The time lines 1,2,3,4 and 5 run from top to bottom, so that later timest are lower down than earlier times t.

At a time t0 the first service user unit 203(a) calls up thecommunication service CALL to establish a connection to a communicationpartner to be specified in parameters. This call is sent via a prompt310 containing further parameter from the service user unit 203(a) tothe assigned first service provider unit 220(a) received by the firstinterface 204(a) of the first service provider unit 220(a). As it isalready known in the first service provider unit 220(a) on the secondlogical level LYR2 due to a previous registration of the service userunit 230(a) which coding methods or codecs the service user unit 230(a)uses or a preferred sequence for their use, it is not necessary for theservice user unit 230(a) specify these parameters in the previous prompt310 and they do not have to be specified additionally in every methodcall.

The service provider unit 220(a) receives the request for a service callsent with the prompt 310, processes the parameters contained in theprompt 310 and at a time t1 generates a further prompt 312 directed tothe first logical level LYR1, which is received at the first interfaceIF1 of the SIP master computer 202. This prompt 312 contains aconnection identification number identifying the current connectionrequest, also referred to as Call ID, which is allocated by the serviceprovider unit 220(a).

At a time t2 a confirmation message 312 is transmitted from the firstinterface 204(a) of the first service provider unit 220(a) to the firstservice user unit, generally referred to in specialist circles as anacknowledge message 314. This confirmation message 314 sent from thefirst service provider unit 220(a) via the first interface 204(a)reports the ongoing processing of the connection set-up initiated withthe prompt 310.

During subsequent processing in the first logical level LYR1 all theparameters received with the prompt 312 are extracted from said messageand transformed into a standard SIP invite request. SIP session set-upis then started.

At a time t3 this SIP invite request is generated in the form of aninvite message 316 by the first interface 204(c) of the master computer202 based on the prompt 312 and using the parameters contained thereinand transmitted to the first processing unit 206(c) of the mastercomputer 202. As with the previous comments on the distributed nature ofthe SIP master computer 202, it should be noted here that in analternative embodiment the first processing unit 206(c), the convertingfirst interface 204(c) and the SIP master computer 202 are implementedin distributed systems, which communicate with each other via thepacket-oriented network (not shown).

At a time t4 SIP session set-up is started by the first processing unit206(c) and an invite message 318 is sent to the communication unit 242.The first processing unit 206(c) takes over the role of a SIP proxy inrespect of the communication unit. In the present exemplary embodimentthe communication unit 242 is in the form of a so-called SIP user agent.

At a time t5 a signaling message 320 is sent from the firstcommunication unit 242 to the first processing unit 206(c). Aftersuccessful verification of the readiness of the conimunication unit 242to receive the connection request, the signaling message 320 reportssuccessful signaling of the connection request, which is generallyeffected with call signaling in conventional communication units. In thecase of a preferred implementation of the communication unit in the formof a software application in the exemplary embodiment, a number of othersignaling forms can be implemented in addition to acoustic signaling toindicate an incoming connection request. The signaling message 320 isalso referred to as ringing in SIP terminology, based on conventionalsignaling forms. According to SIP conventions this signaling message iscategorized with code 180.

At a time t6 the signaling message 320 received by the first processingunit 206(c) is forwarded in the form of a further signaling message 322to the first interface 204(c). Optionally some of the parameterscontained in the previous signaling message 320 are modified by thefirst processing unit 206(c) before it is forwarded in the form of thesignaling message 322.

At a time t7 a signaling message 324 is sent by the first interface204(c) to the second interface 204(a) located on the second logicallevel LYR2, in which data from the previous signaling message 322contained in a SIP format is transformed to a format anticipated by thesecond interface 204(a), e.g. XML. The signaling message 324 is nowprocessed in the service provider unit PRX and assigned to thepreviously started communication service using the determined call ID.

Finally at a time t8 acknowledgement of the called communication serviceis given to the calling first service user unit 230(a) in the form of asignaling message 326 by means of signaling to the called communicationunit 242.

If a user of the called communication unit 242 receives the connectionrequest, at times t9, . . . , t12 respectively confirmation messages328, 330, . . . , 334 are sent from the communication unit 242 to thefirst service user unit 230(a). The first confirmation message 328,structured in a SIP format—in SIP terminology also referred to as OK andcategorized as code 200 according to SIP conventions, is similarlyreceived finally as acknowledgment of the called communication servicein the form of the confirmation message 334 at the first service userunit 230(a). If connection set-up is rejected by the calledcommunication unit, a reason for the rejection is contained in the—inthis instance negative—confirmation message 334, which is transmitted inan XML format to the first service user 230(a).

If a positive confirmation message 334 reaches the first service user230(a), at times t13, . . . , t16 respectively backward confirmationmessages 336, 338, . . . , 342 are similarly sent from the first serviceuser unit 230(a) to the communication unit 242. The first confirmationmessage 336 in an XML format is sent by the first service user 230(a),if this latter agrees to the communication connection.

A direct useful data connection PLD1 is then established between thefirst service user 230(a) and the called communication unit 242.

FIG. 4 shows a chronological flow diagram with further reference to thefunctional units in FIG. 2 to illustrate schematically an exchange ofsignaling messages and control messages during the establishment of aconnection between the calling first service user unit 230(a) and thecalled second service user unit 230(b).

The time lines 1,2,3,4 and 5 are assigned in this order to the firstservice provider unit 230(a), the second interface 204(a) of the firstservice provider unit 220(a), the second interface 1F2.2 of the secondservice provider unit 220(b) and the communication unit 242. The timelines 1, 2, 3 and 4 run from top to bottom, so that later times t arelower down than earlier times t.

If as in the present exemplary embodiment, a communication connection isto be established between two service user units 230(a), 230(b),functional units of the first logical level LYR1 are not required. Fromthe point of view of the calling service user unit 230(a) communicationwith the second logical level LYR2 is identical to the exemplaryembodiment in FIG. 4.

At a time t0 the first service user unit 230(a) calls up a communicationservice CALL to establish a connection to a communication partner to bespecified in parameters. This call is sent from the service user unit230(a) to the assigned first service provider unit 220(a) via a prompt410 containing further parameters and received by the first interface204(a) of the first service provider unit 220(a). As it is already knownin the first service provider unit 220(a) on the second logical levelLYR2 due to a previous registration of the service user unit 230(a)which coding methods or codecs the service user unit 230(a) uses or apreferred sequence for their use, it is not necessary for the serviceuser unit 230(a) to specify these parameters in the previous prompt 310and they do not have to be specified additionally in every method call.

The service provider unit 220(a) receives the request for a service callsent with the prompt 410 and processes the parameters contained in theprompt 410. From a paranwter sent to identify the called communicationuser, the second service user unit 230(b), it is particularly clear tothe service provider unit 220(a) that the called user like the callinguser is associated with the third logical level LYR3.

Then at time t1 a prompt 412 is sent to call up a communication serviceon the service provider unit 220(b) associated with the second serviceuser unit 230(b). This prompt 412 contains parameters required for thecommunication connection and is sent from the first interface 204(a) ofthe first service provider unit 220(a) to the second interface IF2.2 ofthe second service provider unit 220(b).

At a time t2 a confirmation message 414 is transmitted from the firstinterface 204(a) of the first service provider unit 220(a) to the firstservice user unit 230(a), which is also referred to in specialistcircles as an acknowledge message 414. This confirmation message 414sent from the first service provider unit 220(a) via the first interface204(a) reports the ongoing processing of the connection set-up initiatedwith the prompt 410.

At a time t3 a prompt 416 is sent from the second interface IF2.2 of thesecond service provider unit 220(b) to the second service user unit230(a). This prompt 416 has an XML structure and forwards the requestinitiated with the prompt 410 to establish a communication connection orcall request directly to the second service user unit 230(b), optionallywith the addition of further administrative parameters by the serviceprovider units 220(a), 220(b).

After successful verification of the readiness of the second serviceuser unit 230(b) to receive the connection request, signaling messages418,420,422 sent at times t4,t5,t6 report successful signaling of theconnection request, which is effected with call signaling inconventional communication units. The signaling messages 418,420,422 aretherefore also referred to as ringing.

If a user of the called second service user unit 230(b) receives theconnection request, at times t7,t8,t9 respectively confirmation messages424,426,428 are sent from the second service user unit 230(b) to thefirst service user unit 230(a). The first confirmation message 424,structured in an XML format—also referred to as OK—is similarly receivedfinally as acknowledgment of the called communication service in theform of the confirmation message 428 at the first service user unit230(a). If connection set-up is rejected by the called second serviceuser unit 230(b), a reason for rejection is contained in the—in thisinstance negative—confirmation message 428.

If a positive confirmation message 428 reaches the first service user230(a), at times t10,t11,t12 respectively backward confirmation messages430,432,434 are similarly sent from the first service user unit 230(a)to the second service user unit 230(b).

FIG. 3 shows a chronological flow diagram with further reference to thefunctional units of FIG. 2 to illustrate schematically an exchange ofsignaling messages and control messages during the establishment of aconnection between the calling communication unit 242 and the calledfirst service user unit 230(a).

It is however assumed with reference to the exemplary embodiment shownaccording to FIG. 5 that the calling communication unit 242 is providedfor an exchange of messages based on the SIP communication protocol. Thecomrminication protocol present in the communication system 200,particularly SIP or H.323, however essentially has no influence on thesuccessful implementation of the inventive method. In particular theinventive method can also be implemented even in the case of a pluralityof different communication protocols, as already set out clearly withreference to the diagram in FIG. 1.

The time lines 1,2,3,4 and 5 are assigned in this order to thecommunication unit 242, the first execution unit 206(c) assigned to theSIP communication master computer 202 the first interface 204(a)assigned to the first service provider unit 220(a), the first interface204(c) assigned to the SIP communication master computer 202 and thefirst service provider unit 230(a). The time lines 1,2,3,4 and 5 runfrom top to bottom, so that later times t are lower down than earliertimes t.

At a time t0 the first communication unit 242 sends a prompt 510 in aSIP format to establish a connection with a communication partner, alsoreferred to as a SIP INVITE. This prompt is sent from the communicationunit 242 to its assigned SIP master computer 202 and received by thelatter's processing unit 206(c). The processing unit takes over the roleof a SIP proxy. The communication partner specified using parameters inthe prompt 510, namely the first service user unit 230(a), is notcontrolled by the processing unit 206(c) of the SIP communication mastercomputer 202, so the prompt 510 is forwarded by this latter at time t1in the form of the largely unmodified processing message 512 to thesecond logical level LYR2, more specifically to the first interface204(a) of the service provider unit 220(a) there.

From the point of view of the first service user unit 230(a) functionalunits in the second logical level LYR2 interact with the first interface204(a) like a proxy, i.e. all the bi-directional signaling messagesdescribed below operate via this level LYR2.

At a time t2 the previously received prompt 512 is forwarded via thefirst interface 204(a) of the communication master computer 220(a) tothe interface 204(c) of the SIP communication master computer 202. Thisforwarding is effected as an appendix to a message, which is otherwiseeffected in a format provided for communication between these twointerfaces 204(a), 204(c), e.g. in an XML format.

In the first logical level LYR1 a SIP INVITE request, i.e. an invitationin the communication protocol SIP, is identified from this appendix tothe message 514 and sends a prompt 516 in XML format at time t3 via theinterface 204(c) to the first interface 204(a) of the communicationmaster computer 220(a) to call up a communication service CALL.

In the service provider unit 220(a) on the second logical level LYR2 acommunication service call—or call request—is identified for thecontrolled service user unit 230(a), whereupon at time t4 acorresponding prompt 518 in an XML format is sent from the firstinterface 204(a) of the communication master computer 220(a) to thefirst service user unit 230(a).

Before an operator or a software application decides to accept thecommunication connection requested by means of the prompt 518, at timet5 a signaling message 520—also referred to as ringing—is sent to thefirst interface 204(a) of the communication master computer 220(a).

At time t6 this signaling message 520 is passed on in the form of aforwarded signaling message 522 to the first logical level LYR1 or tothe interface 204(c).

The signaling message 522 received at the first interface 204(c) isevaluated and a corresponding SIP signaling message 524—categorized ascode 180 according to SIP conventions—is transmitted to the processingunit 206(c) acting as the SIP proxy.

At a time t8 this SIP signaling message 524 in the form of a further SIPsignaling message 526 is forwarded from the processing unit 206(c) tothe SIP communication unit 242.

If a user of the called first service user unit 230(a) receives theconnection request, at times t9, . . . , t12 respectively confirmationmessages 528,530, . . . , 534 are then sent from the first service userunit 230(a) to the communication unit 242. The confirmation massages528, . . . , 534 exchanged at times t9, . . . , t12 correspond in thecounter direction to the exchanged confirmation messages 328, . . . ,334 known from FIG. 3 except that the message are only routed via theinterface 204(a) acting as a proxy in the second logical level LYR2.

At time t9 a first call of a communication service confirming acceptanceof the connection—Response or ok—is sent in the form of the confirmationmessage 528 first to the interface 204(a) acting as proxy in the secondlogical level LYR2, which transmits said confirmation message 528 attime t10 in the form of confirmation message 530 to the interface204(c). The confirmation message 530 received at the first interface204(c) is evaluated and a corresponding SIP confirmation message 532—inSIP terminology also referred to as OK and categorized according to SIPconventions as code 200—is transmitted to the processing unit 206(c)acting as the SIP proxy, from whence it is finally transmitted at timet12 as a SIP confirmation message 534 of the SIP communication unit 242.

If a positive confirmation message 534 reaches the SIP communicationunit 242, at times t13, . . . , t17 respectively backward confirmationmessages 536,538, . . . , 544 230(a).

1. An arrangement for controlling communication connections in apacket-oriented communication system, comprising: at least onecommunication master computer for controlling communication connectionsbased on exchanged signaling messages; and at least one service providerunit for providing communication services for establishing andcontrolling connections based on bi-directional communication servicecalls with at least one service user unit, each service provider unitcomprising an interface to couple the respective unit with the at leastone service user unit, wherein each communication master computercomprises an interface to couple the respective computer with the atleast one service provider unit, wherein each service user unitregisters with the coupled service provider unit such that the serviceprovider unit includes preferred parameters of the respective registeredunit, wherein the at least one service user unit invokes the webservices based communication service via a service call, the servicecall independent of a standard signaling protocol, wherein the at leastone service provider unit having the invoked service sends a messagehaving parameters to the at least one master computer, the messagehaving a protocol independent of the standard signaling protocol,wherein the at least one master computer converts the parameters to astandard signaling protocol message and sends the message to acommunication unit.
 2. The arrangement according to claim 1, wherein theservice provider unit is configured as a proxy master computer unit forcommunication between the at least one service user unit and the atleast one communication master computer.
 3. The arrangement according toclaim 1, wherein the signaling message comprises a sequence of signalingmessages.
 4. The arrangement according to claim 1, wherein the standardsignaling protocol is based according to the SIP protocol or the H.323protocol.
 5. The arrangement according to claim 1, wherein, after asuccessful establishment of a communication connection, a directexchange of payload data between the service user units and/or betweenat least one service user unit and a communication unit assigned to thecommunication master computer is performed.
 6. The arrangement accordingto claim 1, wherein the invoking of the services is based on XML.
 7. Thearrangement according to claim 1, wherein the communication services areweb services.